diff options
Diffstat (limited to 'jpeg/wrgif.c')
| -rw-r--r-- | jpeg/wrgif.c | 399 |
1 files changed, 0 insertions, 399 deletions
diff --git a/jpeg/wrgif.c b/jpeg/wrgif.c deleted file mode 100644 index 5fe8328..0000000 --- a/jpeg/wrgif.c +++ /dev/null @@ -1,399 +0,0 @@ -/* - * wrgif.c - * - * Copyright (C) 1991-1997, Thomas G. Lane. - * This file is part of the Independent JPEG Group's software. - * For conditions of distribution and use, see the accompanying README file. - * - * This file contains routines to write output images in GIF format. - * - ************************************************************************** - * NOTE: to avoid entanglements with Unisys' patent on LZW compression, * - * this code has been modified to output "uncompressed GIF" files. * - * There is no trace of the LZW algorithm in this file. * - ************************************************************************** - * - * These routines may need modification for non-Unix environments or - * specialized applications. As they stand, they assume output to - * an ordinary stdio stream. - */ - -/* - * This code is loosely based on ppmtogif from the PBMPLUS distribution - * of Feb. 1991. That file contains the following copyright notice: - * Based on GIFENCODE by David Rowley <mgardi@watdscu.waterloo.edu>. - * Lempel-Ziv compression based on "compress" by Spencer W. Thomas et al. - * Copyright (C) 1989 by Jef Poskanzer. - * Permission to use, copy, modify, and distribute this software and its - * documentation for any purpose and without fee is hereby granted, provided - * that the above copyright notice appear in all copies and that both that - * copyright notice and this permission notice appear in supporting - * documentation. This software is provided "as is" without express or - * implied warranty. - * - * We are also required to state that - * "The Graphics Interchange Format(c) is the Copyright property of - * CompuServe Incorporated. GIF(sm) is a Service Mark property of - * CompuServe Incorporated." - */ - -#include "cdjpeg.h" /* Common decls for cjpeg/djpeg applications */ - -#ifdef GIF_SUPPORTED - - -/* Private version of data destination object */ - -typedef struct { - struct djpeg_dest_struct pub; /* public fields */ - - j_decompress_ptr cinfo; /* back link saves passing separate parm */ - - /* State for packing variable-width codes into a bitstream */ - int n_bits; /* current number of bits/code */ - int maxcode; /* maximum code, given n_bits */ - INT32 cur_accum; /* holds bits not yet output */ - int cur_bits; /* # of bits in cur_accum */ - - /* State for GIF code assignment */ - int ClearCode; /* clear code (doesn't change) */ - int EOFCode; /* EOF code (ditto) */ - int code_counter; /* counts output symbols */ - - /* GIF data packet construction buffer */ - int bytesinpkt; /* # of bytes in current packet */ - char packetbuf[256]; /* workspace for accumulating packet */ - -} gif_dest_struct; - -typedef gif_dest_struct * gif_dest_ptr; - -/* Largest value that will fit in N bits */ -#define MAXCODE(n_bits) ((1 << (n_bits)) - 1) - - -/* - * Routines to package finished data bytes into GIF data blocks. - * A data block consists of a count byte (1..255) and that many data bytes. - */ - -LOCAL(void) -flush_packet (gif_dest_ptr dinfo) -/* flush any accumulated data */ -{ - if (dinfo->bytesinpkt > 0) { /* never write zero-length packet */ - dinfo->packetbuf[0] = (char) dinfo->bytesinpkt++; - if (JFWRITE(dinfo->pub.output_file, dinfo->packetbuf, dinfo->bytesinpkt) - != (size_t) dinfo->bytesinpkt) - ERREXIT(dinfo->cinfo, JERR_FILE_WRITE); - dinfo->bytesinpkt = 0; - } -} - - -/* Add a character to current packet; flush to disk if necessary */ -#define CHAR_OUT(dinfo,c) \ - { (dinfo)->packetbuf[++(dinfo)->bytesinpkt] = (char) (c); \ - if ((dinfo)->bytesinpkt >= 255) \ - flush_packet(dinfo); \ - } - - -/* Routine to convert variable-width codes into a byte stream */ - -LOCAL(void) -output (gif_dest_ptr dinfo, int code) -/* Emit a code of n_bits bits */ -/* Uses cur_accum and cur_bits to reblock into 8-bit bytes */ -{ - dinfo->cur_accum |= ((INT32) code) << dinfo->cur_bits; - dinfo->cur_bits += dinfo->n_bits; - - while (dinfo->cur_bits >= 8) { - CHAR_OUT(dinfo, dinfo->cur_accum & 0xFF); - dinfo->cur_accum >>= 8; - dinfo->cur_bits -= 8; - } -} - - -/* The pseudo-compression algorithm. - * - * In this module we simply output each pixel value as a separate symbol; - * thus, no compression occurs. In fact, there is expansion of one bit per - * pixel, because we use a symbol width one bit wider than the pixel width. - * - * GIF ordinarily uses variable-width symbols, and the decoder will expect - * to ratchet up the symbol width after a fixed number of symbols. - * To simplify the logic and keep the expansion penalty down, we emit a - * GIF Clear code to reset the decoder just before the width would ratchet up. - * Thus, all the symbols in the output file will have the same bit width. - * Note that emitting the Clear codes at the right times is a mere matter of - * counting output symbols and is in no way dependent on the LZW patent. - * - * With a small basic pixel width (low color count), Clear codes will be - * needed very frequently, causing the file to expand even more. So this - * simplistic approach wouldn't work too well on bilevel images, for example. - * But for output of JPEG conversions the pixel width will usually be 8 bits - * (129 to 256 colors), so the overhead added by Clear symbols is only about - * one symbol in every 256. - */ - -LOCAL(void) -compress_init (gif_dest_ptr dinfo, int i_bits) -/* Initialize pseudo-compressor */ -{ - /* init all the state variables */ - dinfo->n_bits = i_bits; - dinfo->maxcode = MAXCODE(dinfo->n_bits); - dinfo->ClearCode = (1 << (i_bits - 1)); - dinfo->EOFCode = dinfo->ClearCode + 1; - dinfo->code_counter = dinfo->ClearCode + 2; - /* init output buffering vars */ - dinfo->bytesinpkt = 0; - dinfo->cur_accum = 0; - dinfo->cur_bits = 0; - /* GIF specifies an initial Clear code */ - output(dinfo, dinfo->ClearCode); -} - - -LOCAL(void) -compress_pixel (gif_dest_ptr dinfo, int c) -/* Accept and "compress" one pixel value. - * The given value must be less than n_bits wide. - */ -{ - /* Output the given pixel value as a symbol. */ - output(dinfo, c); - /* Issue Clear codes often enough to keep the reader from ratcheting up - * its symbol size. - */ - if (dinfo->code_counter < dinfo->maxcode) { - dinfo->code_counter++; - } else { - output(dinfo, dinfo->ClearCode); - dinfo->code_counter = dinfo->ClearCode + 2; /* reset the counter */ - } -} - - -LOCAL(void) -compress_term (gif_dest_ptr dinfo) -/* Clean up at end */ -{ - /* Send an EOF code */ - output(dinfo, dinfo->EOFCode); - /* Flush the bit-packing buffer */ - if (dinfo->cur_bits > 0) { - CHAR_OUT(dinfo, dinfo->cur_accum & 0xFF); - } - /* Flush the packet buffer */ - flush_packet(dinfo); -} - - -/* GIF header construction */ - - -LOCAL(void) -put_word (gif_dest_ptr dinfo, unsigned int w) -/* Emit a 16-bit word, LSB first */ -{ - putc(w & 0xFF, dinfo->pub.output_file); - putc((w >> 8) & 0xFF, dinfo->pub.output_file); -} - - -LOCAL(void) -put_3bytes (gif_dest_ptr dinfo, int val) -/* Emit 3 copies of same byte value --- handy subr for colormap construction */ -{ - putc(val, dinfo->pub.output_file); - putc(val, dinfo->pub.output_file); - putc(val, dinfo->pub.output_file); -} - - -LOCAL(void) -emit_header (gif_dest_ptr dinfo, int num_colors, JSAMPARRAY colormap) -/* Output the GIF file header, including color map */ -/* If colormap==NULL, synthesize a gray-scale colormap */ -{ - int BitsPerPixel, ColorMapSize, InitCodeSize, FlagByte; - int cshift = dinfo->cinfo->data_precision - 8; - int i; - - if (num_colors > 256) - ERREXIT1(dinfo->cinfo, JERR_TOO_MANY_COLORS, num_colors); - /* Compute bits/pixel and related values */ - BitsPerPixel = 1; - while (num_colors > (1 << BitsPerPixel)) - BitsPerPixel++; - ColorMapSize = 1 << BitsPerPixel; - if (BitsPerPixel <= 1) - InitCodeSize = 2; - else - InitCodeSize = BitsPerPixel; - /* - * Write the GIF header. - * Note that we generate a plain GIF87 header for maximum compatibility. - */ - putc('G', dinfo->pub.output_file); - putc('I', dinfo->pub.output_file); - putc('F', dinfo->pub.output_file); - putc('8', dinfo->pub.output_file); - putc('7', dinfo->pub.output_file); - putc('a', dinfo->pub.output_file); - /* Write the Logical Screen Descriptor */ - put_word(dinfo, (unsigned int) dinfo->cinfo->output_width); - put_word(dinfo, (unsigned int) dinfo->cinfo->output_height); - FlagByte = 0x80; /* Yes, there is a global color table */ - FlagByte |= (BitsPerPixel-1) << 4; /* color resolution */ - FlagByte |= (BitsPerPixel-1); /* size of global color table */ - putc(FlagByte, dinfo->pub.output_file); - putc(0, dinfo->pub.output_file); /* Background color index */ - putc(0, dinfo->pub.output_file); /* Reserved (aspect ratio in GIF89) */ - /* Write the Global Color Map */ - /* If the color map is more than 8 bits precision, */ - /* we reduce it to 8 bits by shifting */ - for (i=0; i < ColorMapSize; i++) { - if (i < num_colors) { - if (colormap != NULL) { - if (dinfo->cinfo->out_color_space == JCS_RGB) { - /* Normal case: RGB color map */ - putc(GETJSAMPLE(colormap[0][i]) >> cshift, dinfo->pub.output_file); - putc(GETJSAMPLE(colormap[1][i]) >> cshift, dinfo->pub.output_file); - putc(GETJSAMPLE(colormap[2][i]) >> cshift, dinfo->pub.output_file); - } else { - /* Grayscale "color map": possible if quantizing grayscale image */ - put_3bytes(dinfo, GETJSAMPLE(colormap[0][i]) >> cshift); - } - } else { - /* Create a gray-scale map of num_colors values, range 0..255 */ - put_3bytes(dinfo, (i * 255 + (num_colors-1)/2) / (num_colors-1)); - } - } else { - /* fill out the map to a power of 2 */ - put_3bytes(dinfo, 0); - } - } - /* Write image separator and Image Descriptor */ - putc(',', dinfo->pub.output_file); /* separator */ - put_word(dinfo, 0); /* left/top offset */ - put_word(dinfo, 0); - put_word(dinfo, (unsigned int) dinfo->cinfo->output_width); /* image size */ - put_word(dinfo, (unsigned int) dinfo->cinfo->output_height); - /* flag byte: not interlaced, no local color map */ - putc(0x00, dinfo->pub.output_file); - /* Write Initial Code Size byte */ - putc(InitCodeSize, dinfo->pub.output_file); - - /* Initialize for "compression" of image data */ - compress_init(dinfo, InitCodeSize+1); -} - - -/* - * Startup: write the file header. - */ - -METHODDEF(void) -start_output_gif (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo) -{ - gif_dest_ptr dest = (gif_dest_ptr) dinfo; - - if (cinfo->quantize_colors) - emit_header(dest, cinfo->actual_number_of_colors, cinfo->colormap); - else - emit_header(dest, 256, (JSAMPARRAY) NULL); -} - - -/* - * Write some pixel data. - * In this module rows_supplied will always be 1. - */ - -METHODDEF(void) -put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo, - JDIMENSION rows_supplied) -{ - gif_dest_ptr dest = (gif_dest_ptr) dinfo; - register JSAMPROW ptr; - register JDIMENSION col; - - ptr = dest->pub.buffer[0]; - for (col = cinfo->output_width; col > 0; col--) { - compress_pixel(dest, GETJSAMPLE(*ptr++)); - } -} - - -/* - * Finish up at the end of the file. - */ - -METHODDEF(void) -finish_output_gif (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo) -{ - gif_dest_ptr dest = (gif_dest_ptr) dinfo; - - /* Flush "compression" mechanism */ - compress_term(dest); - /* Write a zero-length data block to end the series */ - putc(0, dest->pub.output_file); - /* Write the GIF terminator mark */ - putc(';', dest->pub.output_file); - /* Make sure we wrote the output file OK */ - fflush(dest->pub.output_file); - if (ferror(dest->pub.output_file)) - ERREXIT(cinfo, JERR_FILE_WRITE); -} - - -/* - * The module selection routine for GIF format output. - */ - -GLOBAL(djpeg_dest_ptr) -jinit_write_gif (j_decompress_ptr cinfo) -{ - gif_dest_ptr dest; - - /* Create module interface object, fill in method pointers */ - dest = (gif_dest_ptr) - (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, - SIZEOF(gif_dest_struct)); - dest->cinfo = cinfo; /* make back link for subroutines */ - dest->pub.start_output = start_output_gif; - dest->pub.put_pixel_rows = put_pixel_rows; - dest->pub.finish_output = finish_output_gif; - - if (cinfo->out_color_space != JCS_GRAYSCALE && - cinfo->out_color_space != JCS_RGB) - ERREXIT(cinfo, JERR_GIF_COLORSPACE); - - /* Force quantization if color or if > 8 bits input */ - if (cinfo->out_color_space != JCS_GRAYSCALE || cinfo->data_precision > 8) { - /* Force quantization to at most 256 colors */ - cinfo->quantize_colors = TRUE; - if (cinfo->desired_number_of_colors > 256) - cinfo->desired_number_of_colors = 256; - } - - /* Calculate output image dimensions so we can allocate space */ - jpeg_calc_output_dimensions(cinfo); - - if (cinfo->output_components != 1) /* safety check: just one component? */ - ERREXIT(cinfo, JERR_GIF_BUG); - - /* Create decompressor output buffer. */ - dest->pub.buffer = (*cinfo->mem->alloc_sarray) - ((j_common_ptr) cinfo, JPOOL_IMAGE, cinfo->output_width, (JDIMENSION) 1); - dest->pub.buffer_height = 1; - - return (djpeg_dest_ptr) dest; -} - -#endif /* GIF_SUPPORTED */ |